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Science Unit 3
Grade Eight Science Questions, Unit Three out of Five
What are the two main types of lenses?
Concave lenses and convex lenses.
What is 'light?'
Light is a form of energy you can see.
What does a convex lens do?
A convex lens converges light.
What does a concave lens do?
A concave lens diverges the light.
What type of lens is in the human eye?
A human eye has a convex lens.
What does the lens of the human eye do?
The lens of the human eye refracts light to the retina.
If you are near sighted, that means the light which is refracted does what?
The image forms before the retina because the eye is too long and the refracted light does not
meet the retina.
If you are far sighted, that means the light which is refracted does what?
The image forms behind the retina because the eye is too short and the refracted light does
notmeet the retina.
The camera and the eye both have a lens. True or False?
True
The camera and the eye both have a type of shutter. True or False?
True
The _______ has a retina. The eye or the camera?
The eye has the retina.
The ______ uses a film. The eye or the camera?
The camera uses a film.
The _______ has a diaphragm. The eye or the camera?
The camera has a diaphram.
The ______ has an iris. The eye or camera?
The eye has an iris.
The ______ has a ciliary muscle. The eye or the camera?
The eye has a ciliary muscle.
The ______ uses a focusing ring. The eye or the camera?
The camera uses a focusing ring.
The ______ has an optic nerve. The eye or the camera?
The eye has an optic nerve.
The process of changing the shape of your lens is called what?
Accommodation
The shortest distance at which an object is in focus is called _______?
The near point of the eye.
The longest distance at which an object is in focus is called _______?
The far point of the eye.
What part of the eye moves to change the distance of the lens from the retina, changing the shape
of the lens, allowing you to focus?
The ciliary muscle.
The diaphragm is a device that controls what?
It controls the opening of the lens or optical system.
The shutter is a device that limits the ______ __ ______?
Passage of light.
What part of the eye functions like the diaphragm of a camera, controlling the amount of light
that enters the eye?
The iris.
What part of the eye functions like the shutter of a camera?
The eyelid.
The natural adjustment in the size of the pupils is called what?
It is called iris reflex.
What part of the eye senses light?
The retina senses light.
What is the point called that does not have any light sensing skills?
The blind spot.
Binoculars are what two kind of telescopes mounted together.
Reflecting telescopes.
What happens in a refracting telescope?
Light from afar is focused through a convex lens called an objective lens.
What other type of lens in a refracting telescope works as a magnifying glass?
The eyepiece lens.
What happens in a reflecting telescope?
Light from afar is collected through a concave lens called the objective mirror.
Binoculars use what to serve as plane mirrors?
Glass prisms
What part of the microscope do you look through?
The eyepiece/ocular lens
What part of the microscope holds the eyepiece and the objective lenses at the proper distance
from each other?
The tube.
What part of the microscope moves the stage up or down?
Course-adjustment knob.
What part of the microscope do you use with high and medium power magnification to bring the
object into focus.
Fine-adjustment knob
What part of the microscope connects the base to the tube?
The arm
What part of the microscope rotates a disk holing the objective lenses.
Revolving nosepiece.
What part of the microscope magnifies the object?
Objective lens.
What part of the microscope supports the microscope slide?
The stage.
What part of the microscope directs light to the object being viewed?
Condenser lens.
What part of the microscope controls the amount of light reaching the object being viewed.
The diaphragm.
What part of the microscope shines light through the object to see the details better?
The light source.
What is 'light?'
Light is a form of energy you can see
What is a natural light source?
A natural light source is a non-man-made source of light.
Give the definition of radiate.
To send out energy in the form of waves or rays.
Give the definition of radiation.
The transfer of radiant energy.
Give the definition of radiant energy.
Energy transferred or emitted as waves or rays in all directions
Give the definition of bioluminesence.
Light being emitted produced by chemical reactions within a living creature. For example, an
angler fish.
Give the definition of chemiluminesence.
Chemical reactions that give off visible light energy.
Give the definition of luminous.
Giving off it's own light.
Give the definition of non-luminous.
A substance that does not give off it's own light.
Give the definition of incandescent.
The emission of visible light by a hot object.
Give the definition of fluorescent.
The process in which high-energy, ultraviolet light is absorbed by an object, which emits
some of the light, causing the object to glow.
Give the definition of phosphorescent.
The persistent emission of light following the exposure to and remove of a source of
radiation.
What is the first basic principle of light?
Light is a form of energy.
The brightness of intensity of light indicates what?
It indicates how much energy a surface will receive.
What is an incandescent source of light?
When an object is heated to such a high temperature that it gives off visible light.
What is a fluorescent source of light?
When ultra violet light is absorbed by certain particles, then emits some of the energy,
causing the object to glow.
What is a phosphorescent source of light?
Certain particles can store energy for a while, then when the source of radiation is removed,
the object gives off light.
What is a chemiluminescent source of light?
When a chemical reaction produces energetic particles that give off visible light energy.
What is a bioluminescent source of light?
When a chemical reaction inside living creatures cause them to glow.
How do you calculate the cost of lighting.
Convert W to KW, calculate the number of KW hours (times KW by hrs); times KW hrs by the cost per KW
hour.
Give the definition of transparent.
An object that allows all the light to pass through.
Give the definition of translucent.
An object that allows some, but not all, light to pass through.
Give the definition of opaque.
An object that allows no any of the light to pass through.
What is a ray?
A straight line that represents the path of a beam of light.
What is the ray model?
A model of light based on the observation that light travels in a straight line.
What is the ray diagram?
A representation of the path of light using a straight line with an arrow.
Give the definition of reflection.
The process in which light strikes a surface and bounces back.
What is the ray called that comes from the light source and strikes the surface?
Incident ray.
What is the ray called that bounces back off the surface.
Reflected ray.
What is the line that meets the surface and makes a 90' angle?
The normal
What is the angle between the incident ray and the normal line called?
Angle of incidence.
What is the angle between the ray of reflection and the normal line called?
Angle of reflection.
Give the definition of a plane mirror.
A mirror having a flat surface.
State the first part of the law of reflection.
1. The angle of reflection is equal to the angle of incidence.
State the second part of the law of reflection.
The incident ray, the normal, and the reflected ray are always in the same plane.
Give the definition of refraction.
The bending of light when it travels from one medium to another.
When light travels from one medium into a denser one, does it bend away or towards the normal?
It bends towards the normal.
When light exits a denser medium, does it travel towards or away from the normal?
Away from the normal.
Who observed that a prism refracted light into different colours?
Sir Isaac Newton.
Give the definition of a spectrum.
When white light is refracted into different colours.
What is the order of the seven colours on the solar spectrum?
Red; Orange; Yellow; Green; Blue; Indigo; and Violet. They are also remembered as ROY G BIV.
The colour you see is based off of what?
Which colours are reflected and which ones are absorbed.
What are the additive colours?
Red, Green, and Blue.
What are the three secondary colours?
Yellow, Cyan and Magenta.
Rods detect what?
Light.
Cones detect what?
Colour.
What is colour blindness?
When the cones in some people's eyes are unable to detect certain colours.
What is a crest?
The high parts of a wavelength.
What is a trough?
The low parts of a wavelength.
What is a wavelength?
The distance from crest to crest.
Give the definition of amplitude.
The height of the crest or the depth of the trough form the rest position.
What is a frequency?
The number cycles completes by a vibrating object in a unit of time.
What is frequency measured in?
Hertz (Hz)
Give the definition of the wave model of light.
A way of explaining the behavior of light.
Give the definition of the electromagnetic spectrum.
Visible light energy and all the visible form of radiant energy.
Decreasing wavelengths are bigger or smaller?
Smaller.
What is infrared radiation?
If you stretch a wave out of 1000nm.
What are radio waves?
Stretching a wavelength even farther than 1000nm.
What are microwaves?
The shortest wavelength an has the highest frequency of all the radio waves.
What are the two different kinds of Remote Imaging Technologies?
RADARSAT; LANDSAT
How are microwaves used?
They are used in radar.
How are radio waves used?
To broadcast television and radio shows.
Wavelengths of 100nm are known as what?
Ultraviolet radiation.
What are X-rays?
X-rays are wavelengths that pass easily through tissue such as skin ans is absorbed by bone.
What is the ozone layer?
It prevents UV rays from reaching the earth's surface.
What are gamma rays?
They have the shortest wavelength and the highest energy of all waves in the electomagnetic
spectrum.
How are gamma rays used?
Doctors use gamma rays to destroy a cancerous tumor. This is called radiation therapy.